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Eliminate most invalidations from loading FixedPointNumbers #35733

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a4e0f47
Eliminate most invalidations from loading FixedPointNumbers
timholy May 4, 2020
cd39cf7
Prevent a few more invalidations
timholy May 4, 2020
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2 changes: 2 additions & 0 deletions base/bool.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,8 @@
# promote Bool to any other numeric type
promote_rule(::Type{Bool}, ::Type{T}) where {T<:Number} = T

convert(::Type{Bool}, x::Bool) = x # prevent invalidation

typemin(::Type{Bool}) = false
typemax(::Type{Bool}) = true

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2 changes: 2 additions & 0 deletions base/char.jl
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Expand Up @@ -49,6 +49,7 @@ Char
(::Type{AbstractChar})(x::Number) = Char(x)
(::Type{T})(x::AbstractChar) where {T<:Union{Number,AbstractChar}} = T(codepoint(x))
(::Type{T})(x::T) where {T<:AbstractChar} = x
AbstractChar(x::AbstractChar) = x

"""
ncodeunits(c::Char) -> Int
Expand Down Expand Up @@ -179,6 +180,7 @@ convert(::Type{AbstractChar}, x::Number) = Char(x) # default to Char
convert(::Type{T}, x::Number) where {T<:AbstractChar} = T(x)
convert(::Type{T}, x::AbstractChar) where {T<:Number} = T(x)
convert(::Type{T}, c::AbstractChar) where {T<:AbstractChar} = T(c)
convert(::Type{AbstractChar}, c::AbstractChar) = c
convert(::Type{T}, c::T) where {T<:AbstractChar} = c

rem(x::AbstractChar, ::Type{T}) where {T<:Number} = rem(codepoint(x), T)
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6 changes: 6 additions & 0 deletions base/essentials.jl
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Expand Up @@ -166,13 +166,16 @@ true
"""
function convert end

convert(::Type{Union{}}, x::Union{}) = throw(MethodError(convert, (Union{}, x)))
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This is my favorite method.

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Yes, this PR has been an exercise in "how on earth can inference discover an ambiguity here?"

convert(::Type{Union{}}, x) = throw(MethodError(convert, (Union{}, x)))
convert(::Type{Any}, x) = x
convert(::Type{T}, x::T) where {T} = x
convert(::Type{Type}, x::Type) = x # the ssair optimizer is strongly dependent on this method existing to avoid over-specialization
# in the absence of inlining-enabled
# (due to fields typed as `Type`, which is generally a bad idea)

Union{}(x::Union{}) = throw(MethodError(convert, (Union{}, x)))

"""
@eval [mod,] ex

Expand Down Expand Up @@ -447,6 +450,9 @@ Stacktrace:
```
"""
sizeof(x) = Core.sizeof(x)
# The next two methods prevent invalidation
sizeof(::Type{Union{}}) = Core.sizeof(Union{})
sizeof(::Type{T}) where T = Core.sizeof(T)
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This'll force us to generate code for each type, and forces us to add a dispatch, which I believe we don't want for it?


# simple Array{Any} operations needed for bootstrap
@eval setindex!(A::Array{Any}, @nospecialize(x), i::Int) = arrayset($(Expr(:boundscheck)), A, x, i)
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13 changes: 13 additions & 0 deletions base/number.jl
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Expand Up @@ -2,6 +2,10 @@

## generic operations on numbers ##

# prevent invalidation
Union{}(x::Number) = throw(MethodError(convert, (Union{}, x)))
convert(::Type{Union{}}, x::Number) = throw(MethodError(convert, (Union{}, x)))

# Numbers are convertible
convert(::Type{T}, x::T) where {T<:Number} = x
convert(::Type{T}, x::Number) where {T<:Number} = T(x)
Expand Down Expand Up @@ -240,6 +244,9 @@ julia> zero(rand(2,2))
"""
zero(x::Number) = oftype(x,0)
zero(::Type{T}) where {T<:Number} = convert(T,0)
# prevent invalidation
zero(x::Union{}) = throw(MethodError(zero, (x,)))
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Suggested change
zero(x::Union{}) = throw(MethodError(zero, (x,)))
zero(x::Union{}) = unreachable

Though I can't promise that defining these might not cause other, unintended, side-effects.

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💯 Agreed, I would hold off on adding these --- they could cause problems, and they're the kind of thing we should be able to handle automatically (i.e. if an argument is bottom, obviously the code is unreachable).

zero(::Type{Union{}}) = throw(MethodError(zero, (Union{},)))

"""
one(x)
Expand Down Expand Up @@ -275,6 +282,9 @@ julia> import Dates; one(Dates.Day(1))
"""
one(::Type{T}) where {T<:Number} = convert(T,1)
one(x::T) where {T<:Number} = one(T)
# prevent invalidation
one(x::Union{}) = throw(MethodError(one, (x,)))
one(::Type{Union{}}) = throw(MethodError(one, (Union{},)))
# note that convert(T, 1) should throw an error if T is dimensionful,
# so this fallback definition should be okay.

Expand All @@ -298,6 +308,9 @@ julia> import Dates; oneunit(Dates.Day)
"""
oneunit(x::T) where {T} = T(one(x))
oneunit(::Type{T}) where {T} = T(one(T))
# prevent invalidation
oneunit(x::Union{}) = throw(MethodError(oneunit, (x,)))
oneunit(::Type{Union{}}) = throw(MethodError(oneunit, (Union{},)))

"""
big(T::Type)
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32 changes: 18 additions & 14 deletions base/reduce.jl
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Expand Up @@ -306,25 +306,29 @@ with reduction `op` over an empty array with element type of `T`.

If not defined, this will throw an `ArgumentError`.
"""
reduce_empty(op, T) = _empty_reduce_error()
reduce_empty(::typeof(+), T) = zero(T)
reduce_empty(op, ::Type{T}) where T = _empty_reduce_error()
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Style nit: I think we usually write short form functions with the braces {} to visually distinguish them:

Suggested change
reduce_empty(op, ::Type{T}) where T = _empty_reduce_error()
reduce_empty(op, ::Type{T}) where {T} = _empty_reduce_error()

reduce_empty(::typeof(+), ::Type{Union{}}) = _empty_reduce_error() # avoid invalidation
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@tkf tkf May 9, 2020 •
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I think we should have this. It is not for avoiding invalidation but for "correctness." I think it's better to do _empty_reduce_error() in sum(Union{}[]) than throwing the MethodError.

reduce_empty(::typeof(+), ::Type{T}) where T = zero(T)
reduce_empty(::typeof(+), ::Type{Bool}) = zero(Int)
reduce_empty(::typeof(*), T) = one(T)
reduce_empty(::typeof(*), ::Type{Union{}}) = _empty_reduce_error()
reduce_empty(::typeof(*), ::Type{T}) where T = one(T)
reduce_empty(::typeof(*), ::Type{<:AbstractChar}) = ""
reduce_empty(::typeof(&), ::Type{Bool}) = true
reduce_empty(::typeof(|), ::Type{Bool}) = false

reduce_empty(::typeof(add_sum), T) = reduce_empty(+, T)
reduce_empty(::typeof(add_sum), ::Type{Union{}}) = _empty_reduce_error()
reduce_empty(::typeof(add_sum), ::Type{T}) where T = reduce_empty(+, T)
reduce_empty(::typeof(add_sum), ::Type{T}) where {T<:SmallSigned} = zero(Int)
reduce_empty(::typeof(add_sum), ::Type{T}) where {T<:SmallUnsigned} = zero(UInt)
reduce_empty(::typeof(mul_prod), T) = reduce_empty(*, T)
reduce_empty(::typeof(mul_prod), ::Type{Union{}}) = _empty_reduce_error()
reduce_empty(::typeof(mul_prod), ::Type{T}) where T = reduce_empty(*, T)
reduce_empty(::typeof(mul_prod), ::Type{T}) where {T<:SmallSigned} = one(Int)
reduce_empty(::typeof(mul_prod), ::Type{T}) where {T<:SmallUnsigned} = one(UInt)

reduce_empty(op::BottomRF, T) = reduce_empty(op.rf, T)
reduce_empty(op::MappingRF, T) = mapreduce_empty(op.f, op.rf, T)
reduce_empty(op::FilteringRF, T) = reduce_empty(op.rf, T)
reduce_empty(op::FlipArgs, T) = reduce_empty(op.f, T)
reduce_empty(op::BottomRF, ::Type{T}) where T = reduce_empty(op.rf, T)
reduce_empty(op::MappingRF, ::Type{T}) where T = mapreduce_empty(op.f, op.rf, T)
reduce_empty(op::FilteringRF, ::Type{T}) where T = reduce_empty(op.rf, T)
reduce_empty(op::FlipArgs, ::Type{T}) where T = reduce_empty(op.f, T)

"""
Base.mapreduce_empty(f, op, T)
Expand All @@ -336,12 +340,12 @@ of `T`.
If not defined, this will throw an `ArgumentError`.
"""
mapreduce_empty(f, op, T) = _empty_reduce_error()
mapreduce_empty(::typeof(identity), op, T) = reduce_empty(op, T)
mapreduce_empty(::typeof(abs), op, T) = abs(reduce_empty(op, T))
mapreduce_empty(::typeof(abs2), op, T) = abs2(reduce_empty(op, T))
mapreduce_empty(::typeof(identity), op, ::Type{T}) where T = reduce_empty(op, T)
mapreduce_empty(::typeof(abs), op, ::Type{T}) where T = abs(reduce_empty(op, T))
mapreduce_empty(::typeof(abs2), op, ::Type{T}) where T = abs2(reduce_empty(op, T))

mapreduce_empty(f::typeof(abs), ::typeof(max), T) = abs(zero(T))
mapreduce_empty(f::typeof(abs2), ::typeof(max), T) = abs2(zero(T))
mapreduce_empty(::typeof(abs), ::typeof(max), ::Type{T}) where T = abs(zero(T))
mapreduce_empty(::typeof(abs2), ::typeof(max), ::Type{T}) where T = abs2(zero(T))

# For backward compatibility:
mapreduce_empty_iter(f, op, itr, ItrEltype) =
Expand Down